The present invention relates to an air flow system used in a microwave oven. A majority of the prior art microwave ovens have been countertop ovens designed to operate while resting upon a countertop. Numerous air flow systems have been utilized in countertop microwave ovens. U.S. Pat. Nos. 3,654,417; 3,681,557; 3,783,219; and 3,829,649 illustrate various air flow systems utilized with countertop microwave ovens of the prior art.
Conventional ovens, in addition to being made in a free-standing style, have been designed to be mounted in a wall. The mounting of a conventional oven within a wall requires that a unique ventilation or air flow system be utilized. Heat must be dissipated out of the wall cavity so that an undue heat build-up is not created within a wall cavity. A ventilating system is especially required where the conventional wall-mounted oven is of the self-cleaning type. In a self-cleaning operation, heat in excess of the normal baking or broiling heat is generated and, hence, must be forced out of the wall cavity. U.S. Pat. Nos. 3,882,843; 3,911,893 and 3,924,601 illustrate several air flow systems used in wall-mounted conventional ovens.
When a microwave oven is mounted in a wall, the air flow systems which are generally utilized in countertop microwave ovens are unsuitable. When the microwave oven is mounted within a wall above a conventional oven, the problem of dissipating heat generated during cooking is increased. The heat dissipation problem is especially difficult when the lower oven is in an open-door broiling operation and a microwave oven mounted above the conventional oven is also operating. During such operation, heat rises from the lower conventional oven and can heat the electronic components of the microwave oven which are already in a heated condition due to their normal operation.